A Multi-Scenario Authenticated Key Exchange Scheme with Forward Secrecy for Fog-enabled VANETs

Vehicle-to-Infrastructure (V2I) and Vehicle-to Vehicle (V2V) communications play crucial roles in Vehicular Ad Hoc Networks (VANETs), enabling real-time data exchange and enhancing road safety. These communication methods necessitate robust authenticated key exchange (AKE) mechanisms to protect user privacy and prevent unauthorized access. Recent research has introduced lightweight V2I AKE schemes that operate without relying on complex asymmetric cryptography. These schemes offer advantages in terms of reduced computational overhead and minimal communication latency. However, their exclusive dependence on long-term secrets compromises forward secrecy, a critical security feature. In response, a novel multiparty V2I AKE protocol based on the ASCON cryptographic algorithm is proposed. Pre-shared keys between entities are dynamically updated at the end of each communication session, achieving forward secrecy while maintaining computational efficiency compared to existing solutions. Additionally, a cross-phase anddual-layerencryptionstrategyisemployedtoimplementconditionalprivacy.Buildinguponthisfoundation,afog-enabledand intra-group V2V AKE framework is proposed. Specifically, fog servers are introduced to manage vehicle grouping and distribute group keys. During the V2V AKE phase, fog servers encrypt and forward ephemeral secrets, ensuring resistance against the intra-group impersonation attack with minimal computational overhead. A comprehensive performance analysis of the proposed scheme demonstrates the superiority over existing solutions across various evaluation metrics.